The use of wind turbines to produce electricity from wind energy is known. The wind turbine is disposed for this purpose with blades, the rotation of which causes a rotor to be driven and as a result of which electric power is obtained. The wind turbine blades are oriented facing the wind, the number of revolutions of the rotor and the delivered power being capable of being regulated by means of a system regulating the angle of attack of each blade in relation to the wind.
There are two main known types of systems regulating the angle of attack of the blades. One of these types are electro-mechanical systems, wherein the blade is driven by a variable-speed electric motor through a planetary gear reducer, with the advantage of electric drive, without the need for a hydraulic unit or internal transmission, but with the drawback of requiring electrical batteries or additional hydraulic systems in emergencies, and with the problem that if the gear reducer is to be moved by another system, it acts as a brake. The second of these types are hydraulic systems that include hydraulic accumulators, which prevent against emergency situations in the absence of electric power, but which have the drawback of using a hydraulic circuit that includes a servo-actuator that drives the blade by means of a swivel coupling that converts the linear movement into a rotary movement, generating unwanted torques.
Patent application EP1988285 A1 describes a device for controlling the blades of a wind turbine, in which each blade is linked to rotational means on its longitudinal axis in order to modify the angle of attack of the blades. The rotational means comprise a hydraulic circuit that includes a safety and emergency control module, a safety and emergency hydraulic accumulator, an electric motor and a hydraulic motor pump as drive means, and an actuator by means of which the blades are rotated.